Commands—introduction
32
•
a reserved field
•
the control field
•
two or more fields to logically conflicting values
If a field has been set to an illegal value:
•
C
HECK CONDITION
status is reported to the host with a sense key of
ILLEGAL REQUEST
and
additional sense of 2400h “invalid field in CDB”.
•
The sense key specific bit is set and the sense key specific bytes will be a field pointer.
•
The command/data bit is set, indicating that the illegal parameter was in the command.
NOTE:
Command descriptor blocks are scanned from left (bit 7) to right (bit 0), and down
(from byte 0 to byte
n
). The field pointer will be set to point to the first bit of the first illegal field
encountered using this scanning route. In some cases, where multiple fixed fields are
contiguous, the field pointer might be set to point to the first bit of the first fixed field in the
group of fixed fields, whereas the actual illegality may lie in a later bit.
Media Access check
This checks if the drive is able to perform media access commands. If the media is inaccessible
then
CHECK CONDITION
status is reported with a sense key of
NOT READY
. The additional sense
will be set to one of the codes associated with the
NOT READY
key.
